With reference to FIG. 6, tooth implantation or bone surgery usually uses a drill bit 10 to drill through a bone (e.g., alveolar bone) 20 to form a fixation hole 21 applied for implantation of bone nail or tooth nail (tooth implant). Friction temperature of the drill bit 10 and the bone 20 will increase with rotary speed of the drill bit 10 and depth of the fixation hole 21, and heat produced by drilling will cause bone necrosis at contacting site of the bone (e.g., alveolar bone) and the bone nail or tooth nail (tooth implant), so a nozzle 30 is used to apply a cooling liquid 40 spraying to the drill bit 10 and the bone 20 for decreasing high temperature caused by friction of the drill bit 10 and the bone 20 in prior art. However, the cooling liquid 40 does not easily permeate into the fixation hole 21 for cooling after the drill bit 10 drill into the bone 20, conventional outer cooling process using the nozzle 30 spraying the cooling liquids 40 may still cause tissue destruction of the bone 20 to decrease fixing strength of bone nail or tooth nail (tooth implant) in the bone 20, and may cause bone necrosis.